This invention relates to a slapper detonator useful for detonating high explosives. Conventionally, most slapper detonators are based on a non-integrated design where a pre-fabricated exploding foil initiator (EFI)/slapper chip is sandwiched between a chip spacer and a barrel. This assembly is then soldered onto a header with a 2-pin feed-through. A problem associated with such modular slapper detonators is the potential for unreliable operation due to failure of the electrical connections between the EFI/slapper chip and the header. Conventionally, electrical connections are formed by soldering. However, it is important to perform this soldering at low temperature to avoid degradation of the dielectric overcoat from which the flyer is generated by the vaporization of the bridge of the EFI. Failure of the solder connections due to materials aging and/or manufacturing defects can lead to unreliable operation of conventional slapper-detonator designs. There is a need for a new approach to slapper detonator design that avoids such problems. The monolithic slapper detonator (monolithic exploding foil initiator) of this present invention can be expected to yield greater reliability of operation and higher yields of devices meeting performance specifications compared to previous modular designs. An additional benefit of the monolithic device embodiments of this present invention is that it is expected to represent a configuration that is more readily survivable in high-g-force environments.